september 24th 20041/27 Modelling Slip- and Creep-mode Shift Speed Characteristics of a Pushbelt Type CVT Bram Bonsen, Tim Klaassen, Koen van de Meerakker, Bram Veenhuizen, Maarten Steinbuch
september 24th 20042/27 Project goal Optimize a pushbelt-type CVT to maximize efficiency by changing the actuation system
september 24th 20043/27 Slip & Efficiency
september 24th 20044/27 Slip & Friction
september 24th 20045/27 CVT actuation changes Reduction of actuation losses by: –Lowering clamping force –Using alternative actuation methods
september 24th 20046/27 Modeling variator What is the expected –Efficiency –Needed actuation forces –Transient response
september 24th 20047/27 Existing models Either –Too complex –Did not describe the effects of slip and its influence on the actuation system
september 24th 20048/27 Transient models Ide Shafai Simplified
september 24th 20049/27 Transient models Ide –Good description of transient behavior when not in slip-mode Shafai –Good description of transient behavior when in slip-mode
september 24th /27 Combination Ide when in creep-mode shifting Shafai when in slip-mode shifting
september 24th /27 Friction / Slip Friction force opposite to slip direction Tangential slip vs Radial slip Torque transmissionvs Shifting
september 24th /27 Testrig
september 24th /27 Measurements
september 24th /27 Measurements
september 24th /27 Measurements
september 24th /27 Friction model Coulomb friction model: Microslip=stiction= creepmode Macroslip=sliding= slipmode
september 24th /27 Microslip shifting mechanism Shifting and torque transmission not related Belt only partially slipping Shifting by elastic deformation of the pulleys Shifting behavior dependent on primary speed
september 24th /27 Macroslip shifting mechanism Slip in both tangential and radial direction Shift speed primary speed independent Shift speed limited by actuation system only
september 24th /27 Model Sliding when force >= friction, Stick when force < friction
september 24th /27 Friction calculation
september 24th /27 Friction calculation Friction Direction
september 24th /27 Identification Minimize output error Number of Parameters limited to 4
september 24th /27 Identification results Very high pulley mass found –Oil in pipes Simplified Ide model used to reduce number of parameters
september 24th /27 Results
september 24th /27 Results
september 24th /27 Conclusions Combined model is more in agreement with the measurements Possibility to investigate more efficient actuation system based on slip
september 24th /27 Recommendations Identification on different transmissions Slip while shifting is incorporated in this model. This can be used to make the actuation more efficient. Optimize the transmission based on the given parameters. (stiffness, length and thickness of pipes, place of actuators etc)